Significant bleeding from rectum of our dog.

Question
Our 20 month old Mi-Ki began to bleed profusely during his bowel movements approximately 36 hours ago.  We took him to the vet (regular vet was away on holiday) who said it was colitis from eating scraps of human food.  We were to have him drink only Pedyalite for 24 hours, then introduce special food.  We left feeling he'd be better soon.  That was 20 hours ago, and he's still bleeding from his rectum.  He won't drink the Pedyalite.  He's so small, we are starting to get very concerned.  Is there anything else that could be causing this bleeding?  Any suggestions would be appreciated.  

Answer
Did the vet do a rectal exam?  If not, I would recommend that and possible x-rays.  Blood tests can be done to check his white blood cell count to check for infection as well as check his number of platelets and red blood cell counts to see if he has a bleeding problem.   Most often I will put these dogs on Flagyl (Metronidazole) to help reduce some of the inflammation in the colon...you didn't mention if he was on medication.  Otherwise, you need to get fluids into him.  You can try some fat-free chicken or beef broth, adding honey to his regular water, plain gatorade or see if he will lick ice cubes.   I would also try to get him to eat something very bland such as meat baby food or cooked burger and rice and make sure to give him a lot of plain yogurt to help repopulate the good bacteria in his intestinal tract.